A resistant Corynebacterium species has been isolated with increasing frequency from severely immunosuppressed patients at the Clinical Center. Additional isolates of this organisms are being collected, biochemically characterized, and studied for pattern of antimicrobial susceptibility. A selective medium has been developed to isolate the organisms easily from mixed flora; this will be used to try to identify the organism's normal habitat. BIBLIOGRAPHIC REFERENCE: Hande, K.R., Witebsky, F.G., Brown, M.D., Schulman, C.B., Anderson, Jr., M.D., Levine, A.S., MacLowry, M.D. and Chabner, B.A. Sepsis with a New Species of Corynebacterium. Ann. of Int. Med., 85: 423-426, 1976.